#!/usr/bin/env python3

import os
import pathlib
import subprocess

import common

class Gem5Component(common.Component):
    def add_parser_arguments(self, parser):
        parser.add_argument(
            'extra_scons_args',
            default=[],
            metavar='extra-scons-args',
            nargs='*'
        )

    def do_build(self, args):
        build_dir = self.get_build_dir(args)
        binaries_dir = os.path.join(common.gem5_system_dir, 'binaries')
        disks_dir = os.path.join(common.gem5_system_dir, 'disks')
        os.makedirs(binaries_dir, exist_ok=True)
        os.makedirs(disks_dir, exist_ok=True)
        if args.gem5_source_dir is None:
            if not os.path.exists(os.path.join(common.gem5_src_dir, '.git')):
                if common.gem5_src_dir == common.gem5_default_src_dir:
                    raise Exception('gem5 submodule not checked out')
                common.run_cmd([
                    'git',
                    '-C', common.gem5_default_src_dir,
                    'worktree', 'add',
                    '-b', os.path.join('wt', args.gem5_build_id),
                    common.gem5_src_dir
                ])
        if args.verbose:
            verbose = ['--verbose']
        else:
            verbose = []
        if args.arch == 'x86_64':
            dummy_img_path = os.path.join(disks_dir, 'linux-bigswap2.img')
            with open(dummy_img_path, 'wb') as dummy_img_file:
                zeroes = b'\x00' * (2 ** 16)
                for i in range(2 ** 10):
                    dummy_img_file.write(zeroes)
            common.run_cmd(['mkswap', dummy_img_path])
            with open(os.path.join(binaries_dir, 'x86_64-vmlinux-2.6.22.9'), 'w'):
                # This file must always be present, despite --kernel overriding that default and selecting the kernel.
                # I'm not even joking. No one has ever built x86 gem5 without the magic dist dir present.
                pass
        elif args.arch == 'arm' or args.arch == 'aarch64':
            gem5_system_src_dir = os.path.join(common.gem5_src_dir, 'system')

            # dtb
            dt_src_dir = os.path.join(gem5_system_src_dir, 'arm', 'dt')
            dt_build_dir = os.path.join(common.gem5_system_dir, 'arm', 'dt')
            common.run_cmd(['make', '-C', dt_src_dir])
            common.copy_dir_if_update_non_recursive(
                srcdir=dt_src_dir,
                destdir=dt_build_dir,
                filter_ext='.dtb',
            )

            # Bootloader 32.
            bootloader32_dir = os.path.join(gem5_system_src_dir, 'arm', 'simple_bootloader')
            # TODO use the buildroot cross compiler here, and remove the dependencies from configure.
            common.run_cmd(['make', '-C', bootloader32_dir])
            # bootloader
            common.cp(os.path.join(bootloader32_dir, 'boot_emm.arm'), binaries_dir)

            # Bootloader 64.
            bootloader64_dir = os.path.join(gem5_system_src_dir, 'arm', 'aarch64_bootloader')
            # TODO cross_compile is ignored because the make does not use CC...
            common.run_cmd(['make', '-C', bootloader64_dir])
            common.cp(os.path.join(bootloader64_dir, 'boot_emm.arm64'), binaries_dir)
        common.run_cmd(
            (
                [
                    'scons',
                    '-j', str(args.nproc),
                    '--ignore-style',
                    common.gem5_executable
                ] +
                verbose +
                args.extra_scons_args
            ),
            cwd=common.gem5_src_dir,
            extra_paths=[common.ccache_dir],
        )
        term_src_dir = os.path.join(common.gem5_src_dir, 'util/term')
        m5term_build = os.path.join(term_src_dir, 'm5term')
        common.run_cmd(['make', '-C', term_src_dir])
        if os.path.exists(common.gem5_m5term):
            # Otherwise common.cp would fail with "Text file busy" if you
            # tried to rebuild while running m5term:
            # https://stackoverflow.com/questions/16764946/what-generates-the-text-file-busy-message-in-unix/52427512#52427512
            os.unlink(common.gem5_m5term)
        common.cp(m5term_build, common.gem5_m5term)

    def get_build_dir(self, args):
        return common.gem5_build_dir

if __name__ == '__main__':
    Gem5Component().build()
